1. Field of the Invention
The invention relates to a local area network (LAN). More particularly, the invention relates to a scalable, high performance LAN formed from a parallel bus that has an extended bandwidth advantage permitting utilization of up to 99% of the bandwidth.
2. Brief Description of the Prior Art
Current LAN's are primarily of two types: “token ring” and Ethernet™. Both token ring and Ethernet require specific hardware to be installed into the terminal stations (PC's, Printers, etc.) in order to access the network. The networks are connected as logical rings or a single bus and follow a serial data protocol throughout the network. The presently preferred and most popular network is the Ethernet network.
Ethernet is basically a serial link protocol. It can be implemented in twisted pair wiring, coaxial cable, or glass fiber (FDDI). All cabling must be terminated at each end with an Ethernet transceiver adapter. It operates using broadcast technology, whereby each station transmits in a serial manner and is received simultaneously by all other stations on the immediate network. The transceivers implement carrier-sense multiple access with collision detection (CSMA/CD) technology. Ethernet frames are between 46 and 1500 bytes. Physical connection of Ethernet stations can be from Station to Station, or the network can be connected via a central hub. The stations can detect when the carrier is being used and back off to avoid collision. When a collision is detected by a transceiver, it invokes a back-off algorithm, which causes the transceiver to wait a random period of time before attempting another broadcast on the network.
Although it is virtually the industry standard, Ethernet has several disadvantages:
Studies have shown that during periods of heavy traffic, utilization of the Ethernet can fall to 40% or less of the available bandwidth.
Ethernet requires compatibility of all stations in both hardware and protocol in order for the stations to access the network. For PC's this means an Ethernet compatible NIC (Network Interface Card).
Ethernet requires a dedicated medium (coax, twisted pair, etc.) in order for a station to access the network.
Ethernet hubs are limited in the number of ports that they can accept. Expansion means replacing the hub with a hub of larger capacity or adding another hub, either of which may result in unused capacity.
Bandwidth is limited to the discrete values established by the industry (e.g. 10k, 100k, and 1,000k). To achieve higher bandwidth more and more exotic and expensive technology will be required.